ModSim ass4 taddeus: Source code cleanup.

modsim/ass4_taddeus/ring/ring.c

@@ -4,14 +4,15 @@
 
 //#define DEBUG
 
-#define LOOP 100
-#define STRIDE 10000
-#define REPEAT 7
+#define LOOP 100        // Number of different message sizes
+#define STRIDE 10000    // Difference between the message sizes
+#define REPEAT 7        // Number of times to repeat a measurement
 
 const int data_size = LOOP * STRIDE;
 
 /*
- * The master task measures the time between the sending and receiving of data.
+ * The master task initiates the transport of data and waits for it to come
+ * back. The time between sending and receiving is measured and printed.
  */
 void master(int tasks) {
     double *received = malloc(data_size * sizeof(double)),
@@ -22,7 +23,7 @@ void master(int tasks) {
 
     // generate data to send
     for( i = 0; i < data_size; i++ )
-        sent[i] = (float)i;
+        sent[i] = (double)i;
 
     // Increase the message length with a fixed STRIDE
     for( size = STRIDE; size <= data_size; size += STRIDE ) {
@@ -89,6 +90,7 @@ void slave(int tasks, int rank) {
 int main(int argc, char **argv) {
     int tasks, rank, error;
 
+    // Initialize adnd setup MPI
     if( (error = MPI_Init(&argc, &argv)) != MPI_SUCCESS ) {
         printf("MPI_init failed (error %d)\n", error);
         MPI_Abort(MPI_COMM_WORLD, error);
@@ -98,11 +100,13 @@ int main(int argc, char **argv) {
     MPI_Comm_size(MPI_COMM_WORLD, &tasks);
     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 
+    // Execute the measurements
     if( !rank )
         master(tasks);
     else
         slave(tasks, rank);
 
+    // Finalize mPI
     MPI_Finalize();
 
     return EXIT_SUCCESS;